The present invention relates to an apparatus for dry forming of fibers and/or particles into a non-woven web. A dry forming apparatus is known from U.S. Pat. No. 4,157,724 in which a distributor unit utilizes an upwardly open canister having lower side wall portions of a classification screen material to gradually deposit particle and/or fiber material onto the top surface of a moving, foraminous forming sheet in conjunction with a suction means located underneath the forming sheet. Inside of the distributor container are mounted rotary agitating members. The rotating agitator members act to create a recirculating flow that travels in a first direction along one side of the container and in an opposite direction along the opposite side of the container. Additionally, the agitating elements also impart to the material flow, a movement component directed outwardly toward the side wall portions formed of screen material. Thus, the agitating members serve to keep the material within the distributor container in a flow that is fluidized in air by a whipping action, and at the same time exerts a centrifugal action which results in a continuous throwing of fibers against the screen wall and therethrough. This action of the agitating members increases the output capacity of the distributor beyond that attainable simply by a suction action (as is also known in the art) and because the material moving in the flow along the screen wall portions is substantially evenly distributed inside the container along the screen wall portions, it is ensured that there are no stationary local fiber concentrations to disturb the evenness of the fiber output across the foraminous forming sheet.
While the above-noted, prior art system, operates with a satisfactory output and distribution evenness, it is not without certain disadvantages. These disadvantages relate mainly to the power requirements of the agitating members, which are in the form of impellers having whipping members mounted so as to radially extend from a rotary shaft, necessary for producing the desired dual effects of a recirculating flow within the distributor container and an outward displacement of material from the flow through the screen wall portions. Additionally, since both of these flow producing results are achieved by a common means, the output distribution and the recirculation flow production become necessarily interrelated, thereby reducing the flexibility of the system.
Accordingly, it is the object of the present invention to produce an apparatus of the above-noted, dry forming, type, wherein the good operational qualities may be retained in an advantageously simple manner via a design that is operable in a more flexible manner.
According to preferred embodiments of the present invention, by providing separate means for causing the fiber and/or particle material to be kept in an air fluidized recirculating flow and for removing material from this recirculating flow and directing it outwardly through a distributor screen wall portion onto a moving foraminous forming sheet. Thus, in accordance with the present invention, it is possible to adjust the recirculating flow and outwardly directed flow independently relative to each other, so that the output distribution from the distributor container can be regulated so as to enable the cross-sectional profile of the deposited material layer to be controlled. In accordance with various embodiments disclosed herein, the recirculating flow of material may be produced by an air blower, while the removal of portions of said flow and directing thereof through a screen wall portion to the forming sheet may be achieved by either air nozzles or a rotating needle cylinder.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.